The book covers the general principles of heterogeneous non-catalyzed reactions which are the basis of extractive metallurgy. Table of Contents: 1. Scope 2. Homogeneous Reactions 3. Physical and Physico-chemical Processes 4. Radioactive Decay 5. The Solid Interface 6. The Boundary Layer 7. The Formation of Solid Reaction Products 8. Experimental Methods 9. Solid-Solid Reactions 10. Solid-Gas Reactions 11. Solid-Liquid Reactions 12. Liquid-Gas Reactions 13. Liquid-Liquid Reactions 14. Electrode Processes